1. Field of the Invention
The present invention relates to a method of manufacturing or producing a probe with a minute aperture suitable for use in a scanning near-field optical microscope, an information recording and/or reproducing apparatus using the principle of that scanning near-field optical microscope and the like, a scanning near-field optical microscope using that probe and a recording and/or reproducing apparatus using that probe.
2. Related Background Art
In recent years, a scanning tunneling microscope (hereinafter referred to as STM) has been developed to make it possible to observe the surface of conductive material with sub-nanometer resolution (see U.S. Pat. No. 4,343,993). Thus, the arrangement of atoms on the surface of metal, semiconductor or the like, orientation of organic molecules and the like can be observed on an atomic or molecular scale.
Further, the STM technology has been expanded, and an atomic force microscope (hereinafter referred to as AFM) has been developed to make it possible to observe the surface of an insulating material or the like with a resolution similar to that of the STM (see U.S. Pat. No. 4,724,318).
Further, as the developed STM, a scanning near-field optical microscope (hereinafter referred to as SNOM) has been proposed to examine the surface condition of an object by using evanescent light issuing from a minute aperture formed at a sharp tip of a probe (see Durig, et al., J. Appl. Phys. 59, 3318 (1986)).
Furthermore, a photon STM (hereinafter referred to as PSTM) has been also developed, which is a kind of SNOM for examining the surface of an object by inputting light into the object from its bottom surface through a prism under the condition of total reflection and detecting evanescent light, which exudes toward the object surface, by an optical probe from the side of the object surface (see Reddick, et al., Phys. Rev. B39, 767 (1989)).
In the above SNOM, various kinds of methods for fabricating an optical probe have been devised so far since the resolution is determined by the tip diameter of the optical probe. For example, in order to increase the resolution, no minute aperture is formed at the tip of the optical probe in the PSTM and instead the tip of an optical fiber, which is used as the optical probe, is sharpened by optimizing chemical etching conditions on the end surface of the optical fiber.
Further, at the initial stage of manufacturing an SNOM, the intersection portion between cleaved surfaces of transparent crystal is coated with metal, the metal at the intersection portion is pushed against a hard face and removed therefrom and thus the pushed intersection portion is exposed to form a minute aperture (see European Patent No. 0112402). More recently, a method for forming a minute aperture by using a lithographic method has been also used.
Furthermore, a method for fabricating an optical probe by constructing integrate minute aperture and light waveguide has been proposed (see U.S. Pat. No. 5,354,985).
However, in the above conventional technologies, where no minute aperture is formed in the optical probe as in the PSTM, stray light other than the evanescent light, such as light scattered by an uneven portion of the object surface, is undesirably detected and the resolution is likely to be lowered.
Further, in the method in which the optical fiber is etched, it is difficult to fabricate an integrated and compact optical probe.
In the conventional method of forming the minute aperture in which the cleaved surfaces of the crystal is used, the size of the diameter of the minute aperture is apt to vary and its yield is not good. In addition, integration and compact construction are hard to attain.
Further, in the conventional method of forming the minute aperture using the photolithography, the limit in the diameter of the aperture is about 100 nm due to the limitation in precision of its processing apparatus, and thus it is difficult to fabricate the minute aperture with a diameter of about 10 nm. Hence, there is a limitation of the resolution of the SNOM apparatus. Furthermore, the processing is apt to be complicated, considerable time is required and its cost is relatively high.
If EB (electron beam) processing apparatus or FIB (focused ion beam) processing apparatus is used, it is in principle possible to form an aperture of less than 100 nm. However, the positional alignment control is complicated and variation is likely to occur. Further, yield is not good since the processing is performed point by point.